Air Apparent: New Oxygen Systems for the ISS

The rack containing NASA's Oxygen Generation System build for the International Space Station arrives at Kennedy Space Center where it will be installed in a cargo module for launch aboard the space shuttle Discovery.

Credit: NASA/KSC.

Astronauts
aboard the International Space Station (ISS) will be breathing easy after the
next shuttle visit to the orbital research platform.

That flight,
NASA's STS-121
mission currently slated to launch in May, will deliver the U.S.-built
Oxygen Generation System (OGS) to the station in the second of two ISS oxygen upgrades
this year.

"The basic
technologies are the same as the Elektron," said Bob Bagdigian, NASA's project
manager for regenerative environmental control and life support systems, in an
interview.

Built by
Russian engineers, the Elektron
device aboard the space station uses electrolysis to separate water into
hydrogen, which is dumped overboard, and oxygen. The 1,500-pound (680-kilogram)
OGS rack works in much the same way, and will be able to provide 12 pounds of breathable
oxygen daily under normal operations, NASA officials said.

The current
ISS crew, Expedition
12 commander Bill McArthur and flight engineer Valery Tokarev, have also
installed an oxygen conservation system inside the station's U.S.-built Quest
airlock to be used before spacewalks during joint operations with a visiting
shuttle, they added.

NASA's
oxygen factory

Once
installed and operational - a process that could take months - the OGS is
expected to increase the space station's crew capacity up to its maximum
six-person total, NASA officials said.

The largest
ISS crews to date have been three-astronaut expeditions, though extended delays
in station-bound shuttle flights since the 2003 Columbia accident have limited several
missions to two astronauts each.

Bagdigian said
the OGS was originally slated to fly aboard the station's Node 3, a hub for the
bay window-like cupola
and now grounded habitation
module, but was later reworked to function inside the U.S.-built Destiny
laboratory.

The shift
will require some adjustments to Destiny - largely to vent waste hydrogen and
provide power for the OGS - but will allow engineers a chance to shake down the
oxygen system sooner and assist efforts to increase ISS crews sizes, NASA
officials said.

"We know
that oxygen generating systems in general have a lot of problems over the years
during start-up," said William Gerstenmaier, NASA's associate administrator for
space operation, in a press conference last week. "We think we'll have some
problems with our oxygen generator system. We want to fly it early so we can
work those out."

The
Elektron device, for example, caused recurring
headaches for flight controllers and ISS astronauts over several
expeditions when it broke
down repeatedly after in-space repairs. The unit was brought back online,
ultimately in back-up mode, once spare parts were lofted to the ISS.

NASA
officials said the OGS is one of two major parts of a comprehensive life
support system for the ISS. A water reclamation system, which is slated to recycle
wastewater and human urine, is also under development at Marshall Space Flight
Center (MSFC) where the OGS was designed and tested.

Hello
ROOBA

While the
OGS is waiting to launch toward the ISS from NASA's Kennedy Space Center in
Florida, the oxygen-conserving ROOBA system is waiting in orbit for next
shuttle's arrival.

The ROOBA, or
Recharge Oxygen Orifice Bypass Assembly, sounds more complicated than it
actually is, its builders said.

The 25-foot
(7.6-meter) ROOBA uses two hoses to link the space station's Quest airlock -
home base for most ISS spacewalks in U.S.
spacesuits - with a shuttle to draw oxygen directly from the orbiter's
tanks. The measure not only conserves some ISS oxygen supplies, it also eases
strain on airlock equipment that would otherwise have to replaced during the
limited number of flights before NASA retires its shuttle fleet in 2010,
Leonard added.

ROOBA will
be used by astronauts to prepare themselves for spacewalks before they exit the
ISS.

"Before you go outside into a spacewalk, you've got to
breathe oxygen for a few hours to purge the nitrogen out of your blood because
your spacesuit's at a very low pressure," said mission specialist Piers
Sellers, one of two STS-121 spacewalkers, in a NASA interview. "If you didn't
do that, you would get the bends very quickly. So it's important that you
manage to get enough oxygen to purge the nitrogen out of your blood. You
breathe it through a mask."

ROOBA
arrived at the ISS aboard an unmanned Russian-built cargo ship after years of
development work on the ground, though the real test will come during the
STS-121 flight's three planned extravehicular activities, NASA officials said.

"It's
always nice to get a part on orbit," Leonard said, adding that his team will
keep a close watch on ROOBA during the upcoming spacewalks.

Tariq joined Purch's Space.com team in 2001 as a staff writer, and later editor, covering human spaceflight, exploration and space science. He became Space.com's Managing Editor in 2009. Before joining Space.com, Tariq was a staff reporter for The Los Angeles Times. He is also an Eagle Scout (yes, he has the Space Exploration merit badge) and went to Space Camp four times as a kid and a fifth time as an adult. He has journalism degrees from the University of Southern California and New York University. To see his latest project, you can follow Tariq on Google+, Twitter and on Facebook.